JPS5965573A - Igniter of engine - Google Patents

Abstract

PURPOSE:To reduce the burning noise during the drive of an engine by providing the first ignition plug to face to a combustion chamber and the second ignition plug to face to a squish zone for operating the second ignition plug only at the time of high-speed revolution and high load. CONSTITUTION:A cylinder head 5 is fitted on the upper face of a cylinder block 1 to be provided with a partial concave part 4 on which an air inlet port is opened, and a combustion chamber 7 is formed by the concave part 4. A squish zone 8 is formed between the internal wall of the cylinder head 5 excluding the concave part 4 and a piston upper face 3a, and an exhaust port 11 is opened on the internal wall of the cylinder head 5 facing to this zone 8. In the engine with the above-said construction, the first ignition plug 13 to face to the combustion chamber 7 on the cylinder head 5 and the second ignition plug 15 to face to the squish zone 8 in a small concave part 14 shaped on the cylinder head 5 are arranged for the igniting work respectively at the time of normal, high-speed, and high-load operations.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an engine, and more particularly to an ignition device for an engine whose combustion chamber is a partial recess formed in the upper surface of a piston or the inner wall of a cylinder head.

For example, as shown in Japanese Unexamined Patent Publication No. 54-65207, at least one of the upper surface of the piston and the inner wall of the cylinder head facing the upper surface of the piston is partially recessed, and when the piston is at the top dead center, An engine is known in which a combustion chamber formed by the recess and a squish zone having a minute gap are formed between the inner wall of the cylinder head and the upper surface of the piston.

In the engine with the above structure, the combustion chamber is formed compactly and the flame propagation distance is shortened, and the squish flow from the squish zone is introduced into the combustion chamber to increase the combustion speed, resulting in self-ignition of the air-fuel mixture. Therefore, it becomes possible to set the compression ratio high, increasing thermal efficiency and improving fuel efficiency.

However, when the above-mentioned engine is operated at high speeds and loads, such as when driving on a highway,
Originally, the engine was operated at a high compression ratio and the charging efficiency was extremely high, resulting in an extremely high combustion rate and a problem with loud combustion noise.

The present invention has been made in view of the above-mentioned concerns, and provides an engine having a combustion chamber consisting of a partially recessed portion and a squish zone as described above, while achieving both high compression and anti-knocking functions. It is an object of the present invention to provide an ignition device for an engine that can reduce combustion noise at high speeds and high loads.

In the engine ignition system of the present invention, in the engine as described above, a first spark plug conventionally provided facing the combustion chamber is provided with a second spark plug facing the squish zone. The control device for controlling the operation of the spark plugs is characterized in that only the second spark plug is activated during high rotation and high load, and the conventional first spark plug is activated during other normal operations. It is something.

When ignition is performed using only the second spark plug as described above at high speeds and high loads, the flame propagates from the ignition spark over a long distance (from the flat squish zone to the small recessed combustion chamber).
What's more, combustion is now carried out in a curved space, which lowers the combustion speed and reduces combustion noise.

When the first spark plug is activated during normal driving such as city driving, the flame propagation occurs in the same way as in the conventional German engine, and thermal efficiency is improved by reducing compression.
The effect of improving fuel efficiency is maintained.

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows an engine equipped with an ignition device according to one embodiment of the invention. A cylinder 2 is formed in the cylinder block 1, and a piston 3 is fitted into the cylinder 2. A cylinder head 5 having a partial recess 4 in the inner wall facing the upper surface 3a of the piston 3 is fixed to the upper surface of the cylinder block 1 via a gasket 6. A portion of the inner wall of the cylinder head 5 excluding the recess 4 is formed approximately parallel to the piston top surface 3a, and when the piston 3 is at the top dead center as shown in the figure, the portion excluding the recess 4 forms a minute gap with the piston top surface 3a. and face each other. In this way, a compact combustion chamber 7 is formed by the recess 4, and a squish zone 8 with a minute gap is formed between the inner wall of the cylinder head 5 other than the recess 4 and the piston top surface 3a.

An intake boat 9 opens in the four parts 4, and the intake boat 9
is equipped with an intake valve 10. On the other hand, an exhaust boat 11 is mounted on the inner wall of the cylinder head 5 facing the squish zone 8.
is opened, and the exhaust boat 11 is equipped with an exhaust pulp 12.

According to the above structure, since the combustion chamber 7 is formed compactly by the partial recess 4, the distance of flame propagation from the ignition plug is shortened, and moreover, a high-speed airflow is generated from the squish zone 8 to the combustion chamber 7 at the end of the compression stroke. Since the combustion rate is increased by the introduced squish effect, knocking due to self-ignition of the air-fuel mixture is prevented, making it possible to achieve high compression.

FIG. 2 shows a cylinder head with 5 volumes as seen from the cylinder block 1 side, and FIG. 3 is a cross-sectional view taken along the line A--A. As shown in FIGS. 2 and 3, the recess 4
A first spark plug 13 is disposed so as to face the combustion chamber 7 consisting of a cylinder head 5, and a second spark plug 15 is disposed in a small recess 14 formed in the inner wall of the cylinder head 5 so as to face the squish zone 8. There is.

The first and second spark plugs 13.15 are ignited by an ignition control device as shown in FIG. The operation of the spark plug 13.15 will be explained below with reference to FIG.

First, normal operation without high rotation and high load will be explained. A rotation speed signal S1 outputted by a rotation sensor 20 consisting of a combination of a pulse generator and a counter attached to the engine crankshaft, etc. is the first signal of the ignition timing setting circuit 21.
The load signal S2 that is input to the setting device 22 and output from the load sensor 23 that detects the engine load by detecting the throttle opening or intake negative pressure, for example, is the same (the second setting device 24 of the ignition timing setting circuit 21 These first,
The second setter 22, 24 outputs advance signals S3, S4 that advance the ignition timing from top dead center according to the engine speed and load, respectively, according to the settings shown in FIGS. 5 and 6, for example. Such a lead M pattern can be stored in a microcomputer or the like as a calculation formula or a map, and such electronic lead angle control has been conventionally performed. The advance angle signals S3 and S4 are added in an adder 25, and the ignition timing setting circuit 21 outputs the output of the adder 25, that is, the ignition timing that optimally sets the ignition timing in accordance with both the engine speed and the load. Signal S5
is output.

The ignition timing signal S5 is input to a drive circuit 28 of an ignition drive device 27 through a correction circuit 26a of a correction device 26, which will be described later. At the same time, this drive circuit 28 includes a crank angle sensor 29, which is composed of, for example, a combination of a magnet attached to the engine crankshaft and a signal detection coil.
A crank angle signal S6 outputted by is inputted. The drive circuit 28 operates the power transistor 300 at a predetermined timing based on the crank angle signal S6 and the ignition timing signal S5.
It outputs an ignition signal S7 that controls the base current. This power transistor 30 has a collector current depending on the base current, that is, the primary coil 31 of the ignition coil 31.
The primary current flowing through a is cut off, surface pressure is generated on the secondary coil 31b side, and the first spark plug 13 is activated to ignite.

That is, the switching circuit 32 provided between the secondary coil 31b and the spark plug 13.15 detects the high rotation speed of the high rotation detector 33 which receives the rotation speed signal S1 and detects high engine rotation speed (for example, 4500 rpm or more). AND in which the signal S8 and the high load signal S9 of the throttle fully open detector 34 that receives the load signal S2 and detects the fully open throttle state are input.
It is designed to be switched by the output S10 of the gate 35, and when the engine is not operated with the high rotation detector, the output 810 (L level signal) is received and the 2
The secondary coil 31b is connected to the first spark plug 13.

The first spark plug 13 is controlled by an ignition signal S7 formed based on a crank angle signal S6 and an ignition timing signal S5, and advances from the top dead center of the piston 3 by a predetermined amount depending on the rotation speed and load and ignites. Operate.

As mentioned above, during normal operation of an engine that is not at high speed and high load, the first spark plug 13 installed in the combustion chamber 7 consisting of the recess 4 is ignited, so that the engine is completely different from conventional engines of this type. This allows the engine to operate at a high compression ratio while suppressing knocking, resulting in improved fuel efficiency.

On the other hand, when a car is driving on a highway, the engine rotates at high speeds (
As mentioned above, when the engine is operated at a high load with the throttle fully open (for example, 4500 rpm or higher), the high rotation detector 33 and the throttle fully open detector 34 detect this, and the A
The i self-rotation signal S8 and the high load signal S9 are input to the ND gate 35, respectively. By inputting these two signals S8 and S9, the output S10 of the AND gate 35 is replaced with an H level signal. By inputting this H level output Slo, the switching circuit 32 switches the secondary coil 31b to the second
The second spark plug 15 is switched to be connected to the spark plug 15 (the state shown in FIG. 4), and the second spark plug 15 is activated instead of the first spark plug 13.

As described above, the first spark plug 13 is deactivated and the second spark plug 13 is inactivated.
When only the spark plug 15 is activated, the flame from the ignition spark spreads through the flat squish zone 8 and into the combustion chamber 7.
As a result, combustion occurs over long distances and in curved spaces, reducing the combustion rate. By lowering the combustion speed in this manner, combustion noise, which tends to be large during operation under -high compression ratio and high charging efficiency, is reduced.

Note that the output 810 of the AND gate 35 is inputted to the above-mentioned correction circuit 26a as well as the switching circuit 32. The correction circuit 26a sends the output S5 of the adder 25 as it is to the drive circuit 28 when the output S1o is an L level signal, that is, when the engine is normally operated. However, when the engine is operated at high speed and high load as described above and the output 810 of the AND gate 35 changes to the H level signal, the advance angle characteristic when the throttle is fully open is corrected to the advance side as shown in FIG. This correction amount is, for example, about 100, but by correcting and advancing the ignition timing in this way, the output performance of the engine improves, and the reduction in output due to lowering the combustion speed to reduce combustion noise is avoided. Compensated.

Note that the advance angle correction during high rotation and high load as described above is not necessarily necessary, and may be performed as necessary. Further, in the above embodiment, the first
Although only the spark plug 13 is set to be ignited, it goes without saying that both ignition graphs 13 and 15 may be ignited during normal operation. Further, the ignition device of the above embodiment has a cylinder head 5.
Although the ignition device of the present invention is used for an engine in which a recess 4 forming a combustion chamber 7 is formed, it is also possible to form a recess in the piston 3 as is conventionally known. Of course, the present invention can also be applied to such an engine.

As explained in detail above, the engine ignition system of the present invention is effective for increasing the pressure of an engine having a partially recessed combustion chamber and a squish zone, and reducing combustion noise at high speeds and high loads while maintaining the non-king prevention function. This greatly increases the practical value of the engine in this building.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal sectional view showing an engine in which the engine ignition system of the present invention is used, FIG. 2 is a plan view showing a part of an embodiment of the present invention, and FIG. 3 is a line A-A in FIG. 2. FIG. 4 is a block diagram schematically showing the ignition control device of the above embodiment. FIGS. P to 7 are graphs showing four ignition timing advance patterns in the above embodiment. 3...Viston 3a...Piston top surface 4.
...Concave part 5...Cylinder head 7...
・Combustion chamber 8...Squish zone 1
3... First spark plug 15... Second spark plug 20... Rotation sensor 21... Ignition timing setting device 23... Load sensor 27... Ignition drive device Fig. 1 Fig. 2 Figure 3

Claims (2)

[Claims] (1) At least one of the upper surface of the piston and the inner wall of the cylinder head opposite to the upper surface of the piston is provided with a partial recess, and the recess is formed between the inner wall of the cylinder head and the upper surface of the piston when the piston is at top dead center. In an engine configured to form a combustion chamber and a squish zone with a minute gap, a first spark plug is provided in the combustion chamber, and a second spark plug is provided in the squish zone, while during normal operation. An ignition system for an engine, comprising an ignition control device that causes at least the first spark plug to ignite and causes only the second ignition plug to ignite at high speeds and high loads. (2) The ignition control device includes an operating state detector that detects the operating state of the engine, and an ignition system that receives the output of the operating state detector and outputs a signal that carries the optimum ignition timing according to the operating state of the engine. a timing setting device; a correction device that receives the output of the operating state detector and corrects an output signal of the ignition timing setting device in a direction to advance the ignition timing when the engine is at high rotation and high load; and the ignition timing setting device; The engine is characterized by comprising an ignition drive device that activates the first spark plug to ignite during normal operation, and activates only the second ignition plug to ignite during high rotation and high load, with the ignition timing determined by the correction device. An ignition device for an engine according to claim 1.